SureTrack Real Fix: Theft Deterrent Woes

Vehicles have come with factory-installed security systems for many years. As the vehicle gets older, security isn’t much of a concern, but if the system has a problem, it can stop you from driving. Follow this Real Fix to see how a problem with the security system on this old Pontiac Bonneville was diagnosed and repaired.

Vehicle
2000 Pontiac Bonneville SE 3.8L

Title
P1626, Replaced Powertrain Control Module

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found code P1626 – Theft Deterrent Fuel Enable Signal Lost. disconnected the body control module connector, visually inspected the connector and terminals and found no obvious signs of damage. With the key on, engine off, used the multi-meter to measure the voltage at the body control module theft deterrent fuel enable circuit and found the measured voltage was the specified 5 volts. Turned the ignition off and reconnected the body control module connector. With the key on, engine off, used the multi-meter to backprobe the theft deterrent fuel enable circuit at the powertrain control module to measure the hertz frequency, and found the measured frequency was within the specified range of 40-60 hertz. Disconnected the powertrain control module connector, visually inspected the connector and terminals and found no obvious signs of damage. These test results verified the powertrain control module was faulty.

Correction
Replaced the powertrain control module, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.